


The Growing Star

by Volupturex



Category: Undertale (Video Game)
Genre: Feeding, Fluff and Smut, Language, M/M, Mild Smut, Multi, Polyamorous Character, Polyamory, Post-Undertale Pacifist Route, Public Humiliation, Weight Gain, undertum - Freeform
Language: English
Status: In-Progress
Published: 2019-06-13
Updated: 2019-09-05
Packaged: 2020-05-02 08:25:27
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 4
Words: 3,664
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/19195234
Author URL: https://archiveofourown.org/users/Volupturex/pseuds/Volupturex
Summary: A fairly self-indulgent fic about post-pacifist Mettaton growing a bit too accustomed to human food with the help of his human personal assistant.There may be force feeding later on, as well as dubious consent in the form of characters contributing to feeding without their goals (kinks) being fully known. I do not plan on rape in the form of intercourse. This is just to give people a heads up to the consent/lackthereof that may be contained later on--obviously, each chapter will be tagged appropriately.





	1. Pre-Show Snacks

**Author's Note:**

> I don't know a lot yet about where it will go--there will likely be mild smut. I may include other pairings...and chapters will likely be fairly short, so hopefully posted often!

“Are you sure you’re not full, Mettaton? You’ve been eating those all day…” The human eyed the idol with mild concern--indeed, he could see the gentle mound of Mettaton’s stomach cutting into the table already.

“What? Nonsense, Ricky--” A sparkling grin broke through his idle munching, the gloved hand still digging into the candy bowl filled with foil-wrapped chocolates. A bit of dark chocolate was smeared over his otherwise pink lips. “I’m nowhere near capacity!” With a playful wink tossed towards the man, he tossed another candy past his lips...still wrapped. “Mmh, I do like the textures--” The sound of tinfoil crunching in his teeth made his assistant cringe, until finally he reached out to snag the bowl from the robot.

Mettaton had already refocused on his handful of sweets, but he shot his companion a half-lidded pout. “Darling…” He sauntered out from around the table, one hand resting on his little pot-belly, the other sneaking over to take the man’s hand. “It’s just a little snack~ Surely, you can let me indulge?” 

“Mettaton, sir--believe me.” The man pressed a few fingers to his temple before forcing a smile. “It’s my job to get you ready for each show, is it not?” The robot leaned back, lips pursed as he pondered this. “Mhmm….” Thank god he at least acknowledged that. Talking to Mettaton could be like pulling teeth sometimes. “Well, and what would happen if you ate so much you didn’t fit in your costume?” The man had a brief flicker of a smirk--of a ‘ha, gotcha’--but that, unfortunately, was his downfall. Mettaton scoffed; tossing his hair and quickly snatching back the bowl of chocolates, spinning on his heel and marching to the door before turning back to his assistant. “I’m offended, darling, you think I lack the self control to get myself ready. I am a showman, after all--do you think so little of me? I’ll be in my dressing room.” And with that...he slammed the door.

Sigh. Well, he’d made his point. So be it if the stubborn idol ended up embarrassing himself on stage because of his gluttony. Time and again, he’d explained it to Mettaton--but it always seemed to go in one ear and out the other. Human food wouldn’t just be used as fuel for the robot--he wasn’t designed to use that energy. It was processed and stored as excess….and there it stayed. If he accumulated too much? It was his dear assistant’s job to make an appointment with Alphys to remove some of the excess. 

But..Mettaton wasn’t prone to listening, as well the PA knew. He was relatively used to this--he’d lasted longer than the robot’s assistants usually did, because he didn’t get sick of the guy. Mettaton tended to let them quit out of frustration, rather than firing them himself. Well, he had his work cut out for him if he wanted to drive this guy out. He smirked to himself, cleaning up some of the foil litter and chocolate smears. Showtime was in a couple hours, and no doubt his boss would be snacking up until the very last minute. 

 

Mettaton smiled into his vanity, delicately applying mascara as he sucked on a large lollipop--the smell of artificial cherry quite pleasant to the robot. He had already gotten dressed, for the most part--a hot pink bustier framed his chest, trimmed with black lace. His exposed belly was still rather rounded, but when he stood, giving a little spin before the floor length mirror behind him (his dressing room was, of course, filled with mirrors), that mound did seem to be...nearly unnoticeable. The robot did notice, however, a moment later...the silvered pants he pulled up were fitting rather tight; his fingers even fumbled over the buttons as he frowned. “That’s odd...didn’t Ricky just buy these? Hmph. I’ll need to make sure he took the right measurements…” Oh, Ricky had. In fact, the assistant had made absolutely certain to get the right size; but since then, Mettaton seemed to have..expanded just slightly. His hips had a little more weight to their sway, and his ass wasn’t quite as toned as it had once been--even giving a little jiggle when the bot, satisfied with his ensemble--flounced from his dressing room. 

“Uh, break a leg, boss…” Ricky, who’d been also making his way to the set, called out--only to be met with a dismissive hand. Well. Looked like Mettaton was still pissy about the chocolates. He’d have to make sure he found something to placate him after the show....something from the burger place, maybe. Once Mettaton had actually tried real surface burgers, the performer fucking loved them--he insisted on Ricky taking him at least once a week, and on getting carryout even more often. It was only a matter of time before that started to head to his waistline, too.


	2. Burgers!

**Summary for the Chapter:**

> Mettaton gets angry and eats burgers. Then he's not so angry. Feat. Burgerpants, who'll probably be more of a fixture in this fic than I originally planned.

Mettaton hurried over to his walk-in closet, mounded tummy bare and bloated-- casting a rather nervous glance to the door. It had been a week since Ricky had admonished him for snacking so often, and for the first time the robot almost felt he’d agree. Almost. The idol wasn’t one to back down from his desires, or admit wrongdoing. At least, not when it came to something so silly as an appetite for sugar! And he just knew the man would find this just hilarious. Well, it wasn’t! He didn’t have a show tonight, thank god--but he would be holding one on one meetings with a good deal of his employees. It was that time of year, apparently--discussing salary and the like--but the thought of so many seeing the way he’d overindulged...well, it wasn’t like he didn’t look _good_. It was just…

Spite. Spite and stubbornness. Ricky wasn’t right, and that really was the crux of the matter. He’d show him! The robot was grinning angrily as he slammed the door to his closet, pounding a fist into his hand. He didn’t need to cover up! He’d own this--and show Ricky he could do a show--or anything--and eat as much as he _damn_ pleased!  
With that, Mettaton grabbed only the soft angora sweater hanging over his chair, stepped into his comfy slip-on black flats--and marched out of his room, making a beeline for the Burger Emporium. Though they were on the surface, now, their location still had the one-off burger joint--though the food was decidedly more edible. The same feline, however, was running the kitchen--and the look of shock and irritation quickly masked with a very false smile was one Mettaton was quite familiar with. “Oh, wipe it. I want a burger, fries and a chocolate shake, doll, and it better be quick.” The pop star looked far more casual than he normally would ever--let alone in public. Luckily, it was near closing; and Mettaton was the only one there; swiveling slightly on the red stool and leaning onto the counter--glaring intently at BP, who just swallowed and turned away--his fur standing up on end. Sheesh. What a weirdo. “Sure thing, boss.” He muttered, shoveling a heaping serving of fries into a bag, fixing the burger--he was too scared to ask what kind of burger, so...the robot was getting all the fixings. He put it all in the takeout bag, greasy brown paper handed over with the thick shake in a cup almost a foot tall--waiting hopefully for Mettaton to take it--and go.

No such luck. Sticking a hand in the bag, Mettaton pulled out a few french fries--they weren’t the freshest, but they were plenty salty, and he ate each one carefully, nibbling them down before moving on to the next. He still looked grouchy, and Burgerpants was doing his best to avoid making eye contact--focusing on cleaning up. Not that there was much mess to clean up; with how few customers they got, he usually kept things sparklingly clean just to keep from getting bored. But looking lazy on the job would no doubt earn him a scolding from the dining robot. Why was he eating this, anyway? Human food was quite good for most monsters, but Mettaton was a robot. What..happened to it?  
Ew. Okay, not thinking about that. A hesitant glance over found Mettaton staring right at Burgerpants--and the cat squeaked, fumbling with his broom a moment. “Uh! Sorry, boss--just got a bit, uhh--distracted! How’s yer, uh, yer meal?”

Silence. Then--a few seconds of grueling awkwardness just stewing, making the cat fidget and squirm under that glare-- “Fine.” Phew. He was moving on to the burger, taking a large bite and--good god, did Alphys give him sharp teeth? At least a few of them seemed..yikes. Burgerpants was trying not to stare, while the bot tore into his food; the sounds of chewing and lips smacking quite evident as the juice dribbled down his chin. Mettaton did grab a napkin, wiping at his mouth as he peeled pickles off the burger, dropping them onto his tongue with a grin--some of his anger seemed to be dissipating, and when he slurped at the rich, chocolatey milkshake, his sigh of contentment was audible even to Burgerpants, who’d tried to busy himself washing potatoes for tomorrow. “That is glorious, darling. I might have to ask you for another burger.”

Another? BP turned, shocked to see Mettaton licking mustard and ketchup off his fingers--he’d pulled his gloves off, and they lay neatly on the counter. His bare, metallic digits were only slightly smeared, and that smirk was a far cry from the near rage he’d entered with. “Uh...I guess, I could...just like that, boss?” He had to wonder why--or, indeed, how--the robot was so hungry. But Mettaton simply nodded, wiping his hands on the napkin and stifling a soft belch. “Oh, dear. Please excuse me--now, quick as you can, doll, I have to be back in my office in half an hour.” Still plenty of time to eat; as witnessed by his first burger, the feline was pretty sure he’d be done this second in under a minute, if he wanted. “Comin’ right up, boss--” He felt a bit less….intimidated, though his employer was always frightening, at least he wasn’t on the warpath any longer. Luckily, he still had some fries, and Burgerpants handed over another baggie of salted potato sticks, hoping that would tide him over while he grilled. Mettaton took them happily enough, a pleased smirk on his lips. “Mmh. I do need to come here more often. I suppose you’ve learned how to actually cook something tasty.” The praise, though back-handed, was well recieved. Burgerpants knew exactly why their food hadn’t been edible before coming to the surface, and it sure hadn’t been his lack of cooking skills. Cough, cough glitter glue burgers, cough. 

But hey. At least the boss liked the food, and damn, was he going at it. It was strange to see his well-groomed boss--the star of the Underground--going at a double cheeseburger like a guy who hadn’t eaten in a week, but...something about the sight was a bit humbling. For Mettaton, anyway. And BP felt a bit smug--knowing his boss had such temptations. He wasn’t, however, expecting the tip. 

A few bills were thrown down as he finished off the shake with a noisy slurp, patting his stomach and licking his lips--the gloss almost worn away--and as he slid from the stool, his landing seemed a bit heavier. “Thank you, darling--close up now, there’s a good boy!” He teased, his voice that saccharine tone that managed to be incredibly threatening. Burgerpants nodded hurriedly, reaching out to scoop up the money--okay, so Mettaton was loaded, but...he’d never thought of his boss as particularly generous. But he’d given him a 200% tip! Okay, so it wasn’t like the meal had cost much anyway, but...still. BP quickly took care of the cash, but his eyes drifted back to the robot currently making his way to the elevator--the cat’s gaze slowly drawn to that swaying booty, plump and...wow. Had his boss always been so bottom heavy? He looked a bit thicker, too--even from behind, he could see the robot’s hand cradling what must have been a bloated food-baby. Damn. 

A few minutes passed, Burgerpants cleaning up and trying not to let his thoughts..get away from him, before he noticed something. Those white gloves, neatly folded, on the counter.  
Shit. He’d have to return those….later.


	3. Backstage!

**Summary for the Chapter:**

> This chapter's a bit shorter, sorry about that! Not a lot but some very mild teasing--but MTT's definitely grown!

“Ohh…dear.” He muttered, grimacing as he tried to zip up his pants--having to use one hand to hold up the pale flesh spilling over his waistband didn’t make it any easier. He sucked in--and not much happened. He still had flab that simply wouldn’t hide under his admittedly poorly-chosen crop top. He could, perhaps, find something long to wear over it… 

The robot pulled on a leather jacket, one that should hug his hips….but when he tried to zip it up, the idol ran into another problem. His zipper just wouldn’t budge, over the paunch in his belly--and not only that, but the hem of the jacket kept riding up and over his hips--where a thicker layer of ‘padding’ gave him a subtle pear shape. “Oh--bother this--” He muttered with frustration, yanking at the zipper aggressively--until there came a knock at the door. Mettaton squeaked, hurriedly seeking out his robe-- but it was too late. In walked Ricky, dressed in show blacks and tapping into his phone. “Boss, we gotta get to the set--you’re on air in 20 and they still have to--” 

Mettaton was frozen; cheeks flushed as Ricky looked up from his phone, his eyes landing squarely on the doughy potbelly his boss sported--only the very bottom of the jacket zipped, with his paunch cradled and on display; soft love handles visible under the hem on either side. For a moment, the pair were silent-- until Ricky broke into a grin, his eyes sparkling with ‘I told you so’. The shorter man swaggered up to Mettaton, and reached for the zipper; unfastening it and slipping the jacket off without so much as a word. He laid it over the chair, and stepped back, eyeing his boss with a hand on his chin. The robot squirmed under his thoughtful gaze--his hands fidgeting. “Well?” Finally, he blurted--frustrated with the silence.

“It looks like you’re gonna have to let it hang, boss--none of your clothes are gonna fit unless they’re skimpy--or pajamas.” He smirked, glancing over to the nearly-empty bag of chips, the bowls of candy that littered his dressing room vanity. “I see you’ve been busy, boss--I guess you just do have a flair for...overindulgence.” Mettaton glared at him, marching over and snatching the chip bag to crumple it up and hurl it into the trash can with all his might--but it fell a bit short. “Oh, don’t get all pissy with me--I warned you, didn’t I? You can get new clothes, but most clothes here aren’t going to fit you perfectly--you’ll need them tailored, anyway. Which means you’ll have to go on air like this. Oh--don’t look at me like that. It’s not the end of the world. There’ll be questions, but you’ll just wave them off as tasting your own cooking too much, or something.” 

Mettaton stared at him, obviously in disbelief. Just go out there? Like this? Not only would his staff question him, but what about his fans? The humans, the monsters--not to mention Alphys! She would scold him dreadfully--and what if there were tabloids? He’d seen how humans wrote about their own celebrities--it was scandal after scandal. He’d already seen his name, but only in context of his splashy entrance into the human world; that wasn’t exactly a negative. And what if--

“Boss.” Ricky had grabbed a lollipop, unwrapping it quickly. “Here. Calm down.” The man held it out to his employer, the smirk having dropped, replaced with a look of tired concern. Mettaton had been fidgeting, muttering--he hadn’t realized anything had been spoken aloud, but..it was always a habit of the robot’s to speak his mind even when he meant to keep his thoughts quiet. Slowly, he took the sucker, giving a few hesitant licks. Peach. He did like the flavor. “I just--Ricky, I don’t want...I don’t want people to focus on--on this.” He pinched his softened belly, giving the chub a resigned jiggle. “I didn’t mean to--grow out of my clothes, I just wanted to--it helps me relax, you know?” He asked hopefully--and Ricky nodded--for once looking rather sympathetic. He had offered the robot candy to de-stress, after all. He knew how that worked. And...honestly, it was kind of cute. A bit humanizing, really, for the robot to have such a habitual coping mechanism. 

“I know, Mettaton. Sir. But in the meantime, we have to film. This isn’t live, so...we’ll have some time to think about how to spin this. I’ll talk with your publicist, okay? And make an appointment with the tailor. But in the meantime, just do your thing. You’re Mettaton--you’re fabulous, you’re glamorous, and just because you’ve got a little cushion doesn’t mean you’re not still going to knock their socks off.”

His little pep talk completed, Ricky offered his boss a smile--relieved to see it returned. “You coming?” With a little sigh--tugging once more at his crop top before leaving it be--he nodded, and flounced out the door--leaving his assistant to pull it shut, following after--and noting the way those thighs rubbed together with his boss’s steps.


	4. Good Morning, Beauties!

**Notes for the Chapter:**

> Sorry for how late this is! I've had this chapter in the works for like, a month; hit some serious writer's block trying to write this one, so I'm going to jump back in with some ideas I find more fun to write!

“Good morning, beauties and gentlebeauties--and welcome to the Underground’s star news network--hosted by yours truly, Mettaton.” The robot bore a rather...calm smile, his hands folded neatly on the desk hiding his ill-fitting suit. He was wearing a pair of pink gloves--he couldn’t find his favorite white pair--and his jacket was a bright blue, with a cheery yellow bowtie. His buttons were undone about halfway down the jacket, and the buttons of his white undershirt were straining over the tubby belly he bore. Luckily, his leggings were nice and stretchy--so the bot’s extra ‘cushion’ wasn’t an issue. 

Behind the cameras, Ricky stood eyeing his boss’s delivery. Despite being aboveground, now, the bot’s studio still broadcast to the Underground with a fascinating blend of their magic and electricity. Mettaton had always been adamant on not abandoning those monsters who remained in the subterranean caverns beneath the mountain, with a team of young monsters helping him out as journalists. Usually, this morning show for the monsters (which meant it was evening on the surface) was an example of the truly bombastic robot’s personality, but...he seemed a bit more sedate. It was a little odd--but luckily, he’d been in a good mood, so perhaps the star was simply feeling a bit.. Low-energy. He’d have to make sure to pep him up...get him to recharge, maybe spend his break shopping. That always got him revved, and...well, it wasn’t like new clothes wouldn’t hurt. 

“That wraps up weather, darlings, so let’s get to the news!” His cheery voice broke Ricky out of his reverie, and he snapped back to attention. Mettaton had taken a sip of coffee--caffeine didn’t have an effect on him, but ever since he’d seen a morning show run by humans, he’d insisted on having a large mug of creamy, sugary coffee--often mocha. His mug was a pastel pink, with white stars, and the robot was incredibly attached. “This weekend is bound to be quite exciting for humans and monsters alike! My very own cousin, DJ Napstablook, is having his first show with a live audience right here in town! Of course, I’ll be there too--but I won’t be the star of the show.” He flashed an almost apologetic wink--but there was no denying the proud smile on his face. He and Blooky might have had their differences--but if there was anyone Mettaton could accept deserving the spotlight more than him--it was his cousin. “So get your tickets, folks! Now, our darling reporters have been working ‘round the clock to get the word out and your opinions, but it’s election season! The monster council needs your votes, darlings--” Mettaton reached delicately into his pink crystal candy bowl, plucking out and crunching down a candy--oof. Ricky winced; the microphone picked that up a bit too well, but Mettaton--though he was sure his boss noticed, perfectionist that he was--just swallowed with a smile before continuing. 

“Now, I know you’ve all been waiting with such utter anticipation for the continuation of my many, award-winning shows now I’m stationed up here on the Surface--and I’m here to announce that the wait is over! Cooking with a K--ahem. Cooking with a Beautiful Robot is going to start airing every Saturday at 3 PM, and we’re going to start experimenting with human food! I’ll have a human taster by my side--but of course, this is going to be food monsters can enjoy as well!” He flashed a wicked grin, before pushing himself back from the desk, giving a little stretch as he stood; arms behind his head. The little paunch was visible, shirt riding up over the smooth, softened mound. “Mmnh--well, that’s all, darlings--I’ll see you all tomorrow morning!” He gave a finger wave, blowing a kiss. “Toodle-oo!” After that--the bot smiled until the cameras cut--quickly tugging down his shirt, cheeks pink as he hurried off set.


End file.
